Preheat your oven to 400°F (200°C).
In a large mixing bowl, combine ground beef, breadcrumbs, Parmesan cheese, parsley, egg, garlic powder, onion powder, salt, and black pepper. Mix until well combined.
Shape the mixture into meatballs about 1 inch in diameter and place them on a baking sheet.
Bake the meatballs for 20 minutes until browned and cooked through.
While the meatballs are baking, heat the French onion soup in a saucepan over medium heat until warmed through.
Transfer the cooked meatballs to the saucepan with the soup and let them simmer for 5 minutes.
Sprinkle mozzarella cheese over the meatballs, cover, and let sit for 2-3 minutes until the cheese melts.